GREENHOUSE EFFECT

What Is Greenhouse Effect??? an atmospheric heating phenomenon, caused by short-wave solar radiation being readily transmitted inward through the earth's atmosphere but longer- wavelength heat radiation less readily transmitted outward, owing to its absorption by atmospheric carbon dioxide, water vapor, methane, and other gases; thus, the rising level of carbon dioxide is viewed with concern.

The Enhanced Greenhouse Effect Carbon dioxide amount has increased after the industrial revolution due to human involvement: –Combustion generating CO 2 Industry Transportation Power generation –Loss of CO 2 sinks Deforestation At present the concentration of CO 2 in the atmosphere is about 385 ppm (parts per million). Before industrialization it was about 280 ppm. Analyses of air contained in ice from the Antarctic ice cap show that there is far more CO 2 in the air today than at any time in the last 650,000 years.

Climate Change - Increasing Concentrations of CO 2 and other Green House Gases (GHG) CO 2 –natural and anthropogenic sources recent increase due to fossil-fuel combustion and deforestation CH 4 –natural and anthropogenic sources –about 1/2 of current emissions are anthropogenic (land fills, natural gas, agriculture) N 2 O –natural and anthropogenic sources -nitrogen-based fertilizers Other important Greenhouse Gases: –CFCs –Ozone –and of course, water vapor!

What would it be like to live without the greenhouse effect ????  Without a greenhouse effect, the Earth have a uniform temperature in the atmosphere of 0 °F instead of the current temp.

Gasses produced by humans

The Enhanced Greenhouse Effect Increased amount of carbon dioxide is leading to global warming of the Earth’s surface because of its enhanced greenhouse effect. Positive feedbacks (those add to warming) 1) Fossil fuel demand in the extreme latitudes would be reduced because heating of our homes would be reduced. 2) Some areas that are currently uninhabitable or unusable for farmland might become suitable for these uses due to warming and weather changes. Some areas could receive much more rainfall than they do currently. Food production could be increased. 3) There might be an increase in yield of some crops due to the increase in the photosynthetic rate of plants to try to keep up with the increased carbon dioxide in the atmosphere. Negative feedbacks (those reduce warming) Most scientists believe that the increase in global temperatures will cause the polar ice caps and glaciers to begin to melt. This will cause sea levels to rise. In the past 100 years ocean levels have already risen about one foot. Because we have built our cities right on the coastlines, many of them would be in peril of serious flooding – if not outright collapse. The rise and expansion of the sea would also allow storm surges and hurricane waves to proceed further inland, causing more damage. Temperature increases can also lead to changes in weather patterns, precipitating more frequent and severe storms. The costs to protect ourselves from flooding and storm damage could be enormous.

 We can presently say that the types and effects of positive feedbacks are more and much pronounced in comparison with the negative feedbacks.  So, in fact if CO 2 levels are doubled, with all feedbacks working, the increase in the surface temperature is not 1.2 ˚C, but 2.5 ˚C.

Factors Affecting Global Temperatures Cloud cover: cooling Changes in Sun’s intensity: cooling or warming Volcanic activity: cooling Sulfate aerosols: cooling

Impacts of Global Warming Melting of polar ice caps Flooding of coastal areas Massive migrations of people Deserts becoming farmland and farmland becoming deserts Alteration of rainfall patterns Significant losses in crop yields

Solutions to Global Warming Reduction of CO 2 emissions –Shifting to alternative energy sources or solving the problem of CO 2 disposal Developing carbon capture and storage: –Underground storage in compressed form –Storage on the bottom of ocean –Storage in giant spheres of dry ice –CO 2 soaked in living organisms.